JPH0424115Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention relates to a fuel supply control device for an internal combustion engine, and in particular controls fuel supply to prevent vehicle speed from becoming higher than necessary. related to things.

<Conventional technology> Conventionally, for example, as shown in FIG.
When the vehicle speed exceeds a second set value (for example, 180 km/h), the fuel injection valve that supplies fuel to the engine stops the commotion and stops the fuel supply, and then the vehicle speed increases to a second set value (for example, 170 km/h). There are some systems that control the fuel supply to be restarted when the vehicle speed drops below the limit, thereby preventing the vehicle speed from becoming higher than necessary and improving safety.

<Problems to be solved by the invention> However, in the case of such fuel supply control, the engine torque suddenly decreases and increases when the fuel supply is stopped and restarted, so the vehicle body loses its natural frequency due to running inertia. It caused large vibrations in the front and rear directions at a frequency matched to that of the previous model, making the car's ride uncomfortable.

The present invention was developed by focusing on these conventional problems, and provides a fuel supply control device for an internal combustion engine that improves riding comfort by alleviating the vibration shock of the vehicle body when fuel supply is stopped and restarted. The purpose is to

<Means for Solving the Problems> Therefore, the present invention, as shown in FIG. Fuel supply stop means B that stops the fuel supply; and fuel supply restart means C that restarts the fuel supply when the vehicle speed after stopping the fuel supply falls below a second set value that is smaller than the first set value.
In an internal combustion engine fuel supply control device comprising:
Immediately after the vehicle speed exceeds the first set value and immediately after the vehicle speed falls below the second set value, the fuel supply stop means B and the fuel supply are configured to intermittent fuel supply and supply stop in accordance with a predetermined cycle. The fuel supply intermittent control means D for controlling the restart means C is provided.

<Operation> In such a configuration, when the vehicle speed detected by the vehicle speed detection means A exceeds the first set value, after that value, the fuel supply intermittent control means D causes the fuel supply stop means B to stop at a predetermined period, e.g. It operates intermittently at a frequency that matches the natural frequency of the vehicle body.

Similarly, immediately after the vehicle speed falls below the second set value after the fuel supply is stopped, the fuel supply intermittent control means D operates the fuel supply restart means C intermittently at a predetermined period.

As a result, immediately after the fuel supply is stopped and immediately after the fuel supply is restarted, fuel supply and supply stop are performed intermittently in a predetermined manner, and as a result, sudden changes in engine torque are suppressed.
This also alleviates the vibration shock of the car body.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 2 showing one embodiment, an internal combustion engine 1 is provided with a crank angle sensor 2 for detecting the engine speed, and an air flow meter 4 for detecting the intake air flow rate is provided in an intake passage 3. Connected. A vehicle speed sensor 6 is provided near the output shaft of the transmission 5 as vehicle speed detection means.

Detection signals from each of these sensors are sent to a control unit 7 with a built-in microcomputer.
The control unit 7 drives the electromagnetic fuel injection valve 8 installed in the intake passage 3 based on each of the detection signals to perform fuel injection control.

In addition, when the vehicle speed reaches a high speed that poses a safety problem,
Control is performed to temporarily stop fuel injection (supply) to prevent the vehicle from reaching a dangerous speed.

The above fuel injection control by the control unit 7 will be explained below with reference to the flowchart shown in FIG.

In step 1 (referred to as S1 in the figure, the same applies hereinafter), the engine speed N and intake air flow rate Q are obtained from the crank angle sensor 2, air flow meter 4, and vehicle speed sensor 6.
and the detection signal of vehicle speed V is read.

In step 2, it is determined whether the vehicle is in a high vehicle speed state where the vehicle speed V exceeds the first set value V ₁ (for example, 180 km/h).

If V>V ₁ , the program proceeds to step 3, sets flag F to 1, and then operates the timer in step 4.

In step 5, it is determined whether the timer value t is 1/4 of the period t ₀ of the natural frequency of the vehicle body. still,
The period t ₀ of the natural frequency of the vehicle body is detected in advance through experiment or analysis.

If t≦t ₀ /2, the process proceeds to step 8, where the pulse width Ti of the injection pulse signal is calculated in order to perform fuel injection in synchronization with normal engine rotation.

This is the engine speed N read in step 1.
It is obtained by correcting the basic injection pulse width Tp=K·Q/N (K is a constant) obtained based on and the intake air flow rate Q using the cooling water temperature and the like.

In step 9, an injection pulse signal having a pulse width Ti is outputted at an injection timing synchronized with the engine rotation, and an amount of fuel corresponding to Ti is injected and supplied from the fuel injection valve 8.

When it is determined in step 7 that t>t ₀ /2, the process proceeds to step 10, where the timer value t is reset to 0, and then proceeds to step 6, where the vehicle speed is set to the second set value V ₂ as described later. Fuel injection will be stopped until the temperature drops below . In other words, from the time the vehicle speed V exceeds the first set value V ₁ until 1/4 of the period t ₀ of the natural frequency of the vehicle body has passed, fuel supply is stopped and the period t ₀
After 1/4 of the period t 0 has elapsed, until 1/2 of the period t ₀ has elapsed, by supplying fuel in synchronization with the engine rotation,
Control is performed to intermittent fuel supply and supply stop in accordance with the period t ₀ .

It should be noted that compared to the period of t ₀ /4<t≦t ₀ /2 during which fuel is supplied, the fuel supply period in synchronization with the rotation of the engine rotating at high speed is sufficiently short, and there is no problem in response.

In this way, since the fuel supply is initially stopped intermittently, the indicated mean effective pressure of the engine is reduced.
Pi becomes as shown in Figure 4, and the apparent slope of Pi immediately after the supply stop control becomes gentle as shown by the dotted line, and as a result, the vibration shock of the vehicle body is reduced as shown by the chain line in Figure 4. Improves ride comfort.

It is also possible to gradually reduce the fuel injection amount and eventually stop the injection, but in this case, there is a risk that the combustion temperature will rise too much due to combustion of a mixture with a lean air-fuel ratio before the injection stops, resulting in burnout. There is.

In this regard, in the case of a system in which fuel supply and stop are performed intermittently, the above-mentioned problems can be avoided.

Next, when the fuel injection is stopped in this way, the vehicle speed decreases and the determination in step 2 becomes NO, and the first set value _V1 is set to be smaller than _V1 with hysteresis. If it falls below the second set value V ₂ (for example, 170 km/h), the judgment in step 11 is
YES.

In step 12, it is determined whether flag F is 1 or not, and if step 6 has been passed, this determination is
If YES, proceed to step 13 and start the timer.

In step 14, it is determined whether or not the timer value t is t≦t ₀ /4. If YES, step 15 is performed.
Proceed to step 8, calculate Ti in the same way as step 8,
In step 16, an injection pulse signal with a pulse width Ti is output to restart fuel injection.

Thereafter, when t > t ₀ /4, the process proceeds to step 17, and while t≦t ₀ /2, the process proceeds to step 18,
Set Ti=0 and temporarily stop fuel injection again.

After t > t ₀ /2, proceed to step 19, reset the timer value to t = 0, and then proceed to step 19.
Proceed to steps 15 and 16 and continue to perform fuel injection control. In other words, from the time the vehicle speed V falls below the second set value V ₂ until 1/4 of the period t ₀ of the natural frequency of the vehicle body has passed, fuel is supplied in synchronization with the engine rotation, and the period t After 1/4 of _{t 0} has elapsed, the fuel supply is stopped until 1/2 of the period t ₀ has elapsed, thereby performing control to intermittent fuel supply and supply stop according to the period t ₀ . .

In this way, since fuel injection is restarted intermittently in the initial stage, the gradient of the apparent effective indicated pressure Pi becomes gentle as shown by the dotted line in Figure 4, similar to the case when fuel supply is stopped. As a result, the vibration shock of the vehicle body is reduced as shown by the chain line in FIG. 4, and ride comfort is improved.

In this case as well, it is possible to prevent burnout due to combustion of a mixture with a lean air-fuel ratio when the injection amount is gradually increased.

Incidentally, if the determination in step 11 is NO or if the determination in step 12 is NO, the process advances to step 15 to perform normal fuel injection control.

In the above flow, the function when going directly from step 5 to step 6, the function when going directly from step 7 to steps 8 and 9, the function when going directly from step 14 to steps 15 and 16, and the function when going from step 17 to step 18. corresponds to the fuel supply intermittent control means. Further, the function of step 6 corresponds to a fuel supply stop means, and the function of step 16 constitutes a fuel supply restart means.

Further, the high vehicle speed state may be detected by detecting the engine speed. This is because at high vehicle speeds such as 170 to 180 km/h, the engine rotational speed is sufficiently higher than the engine rotational speed at normal vehicle speeds.

Furthermore, a configuration may be adopted in which the supply and stop of fuel are intermittent in more stages. Further, the cycle of intermittent supply and stop of fuel is not necessarily limited to the natural frequency of the vehicle body, but it is preferable to set it to a value close to the natural frequency of the vehicle body.

<Effects of the invention> As explained above, according to the invention, since the fuel supply and supply stop are intermittent at predetermined intervals at the initial stage of fuel supply stop and supply restart control at high vehicle speeds, The vibration shock of the vehicle body can be alleviated without any negative effects such as combustion in the engine, and the ride comfort can be improved.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the configuration of the present invention;
The figure shows the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing the fuel injection control routine of the same embodiment, and FIG. 4 shows the fuel injection control at high vehicle speeds of the conventional and the above embodiments. It is a time chart. 1... Internal combustion engine, 6... Vehicle speed sensor, 7... Control unit, 8... Fuel injection valve.

Claims (1)

[Scope of utility model registration request] fuel supply stop means for stopping the fuel supply to the engine when the vehicle speed detected by the vehicle speed detection means is high vehicle speed exceeding a first set value; and the vehicle speed after the fuel supply is stopped is smaller than the first set value. In the fuel supply control device for an internal combustion engine, the fuel supply control device for an internal combustion engine is equipped with a fuel supply reissue means for redistributing the fuel supply when the vehicle speed becomes lower than a second set value.
Immediately after falling below a set value, fuel supply intermittent control means is provided for controlling the fuel supply stop means and fuel supply restart means so as to intermittent fuel supply and supply stop in accordance with a predetermined cycle. Fuel supply control device for internal combustion engines.